Process for manufacturing colored cellulose-ester material



Patented Mar. 9, 1937 PATENT OFFICE I'ROCESS FOR MANUFACTURING COLOREDCELLULOSE-ESTER MATERIAL Henry Dos'ne, Mulhouse, Haut-Rhin, France NoDrawing. Application June 20, 1934, Serial No. 731,531. In Germany July1, 1933 4 Claims.

In the U. S. patent applications Ser. No.

2,042,393, on the name of the same applicant,

there are described two processes for the manufacture of coloredcellulose material, consisting in adding to a viscose mass (alkalinesolution of sodium cellulose xanthogenate) or to an ammoniacal copperoxide cellulose solution, in any phase before coagulation, an.ester-salt of a leuco vat dyestuif or an ester-salt of a body giving byacid oxidation a colored compound, coagulat ing the mass in the usualway and developing the dyeing during or after the coagulation process byacid oxidation.

These processes apply to aqueous solutions of cellulose, to which theabove said ester-salts can be added in form of aqueous solutions without20 dimculties, that is to say, without the risk of precipitations ordecompositions which might adversely ailect the further operations.

In this way perfectly homogeneous mixtures are obtained.

Besides the artificial silk deriving from cellulose and resulting fromaqueous solutions by coagulation, another artificial fibre may beobtained from cellulose compounds, dissolved in organic solvents.Nitro-cellulose for instance is dissolved in a mixture of alcohol andether and pressed through small spinning orifices with subsequentcoagulation. By ventilation the evaporationof the solvent is acceleratedand the previously liquid thread is transformed into artificial yarn. Asa rule acetyl-cellulose is dissolved in acetone or in a mixture ofacetone and alcohol. Usually this solution is either pressed through thespinning apparatus into the open air or into water or another liquid,suitable for absorption of the solvent and for solidifying the remainingcellulose mass forming a thread.

It is however quite impossible to incorporate into a solution of a.cellulose compound in an organic solvent, an aqueous solution of anestersalt, since such addition would lead to a premature coagulation ofthe cellulose mass and would consequently render the subsequent spinningoperation impossible.

It has now been found that organic solvents for ester salts ofleuco-vat-dyestufis are existing, which themselves show the property tobe mixable with the organic solvents such as acetone, alcohol, ether,suitable for dissolving cellulose derivatives. It becomes thereforepossible to unite without difliculties the solution of an ester salt insuch a solvent with the solution of a cellulose derivative, so as toform a homogeneous and inalterable mixture. Solvents having been foundappropriate for dissolving ester-salts are: glycol,glycol-mono-ethylether, glycol diethyl-ether, diethylene-dioxide,pyridine, methylalcohol and others. It has further been found that someester-salts are even sufiiciently soluble in solvents, serving fordissolving the cellulose, such as acetone.

The nature of the ester-salts, especially their alkali salts being thecommercial form of this class of bodies, did not allow any conclusionwith regard to this problem.

' Owing to this discovery, it is possible to combine the production ofartificial fibre, such as acetyl-cellulose and other esterifiedcellulose, nitrocellulose with the simultaneous dyeing of thesematerials.

The development of dyeing and the other aftertreatments required arecarried out according to the usual methods.

According to the present process, colored relief efiects on othermaterials, for instance a textile fabric may be produced, by printingthe cellulose mass containing an ester-salt on this material,coagulating the cellulose mass and developing the dyeing.

Up to now, only two methods for dyeing the said artificial fibres areknown:

(1) Addition of suitable dyestufls to the solution of the cellulosederivative in an organic solvent, either in form of a solution or infinely dividedform, afterwards coagulating the cellulose mass andcontinuing as usual.

2) Dyeing of the manufactured finished artificial silk material by meansof suitable dyestufls.

These methods, applied so far, however show a number of disadvantages.

With regard to the first method, it must be considered that onlydyestufis, being sufi'iciently soluble in the cellulose solvent, can beused. Naturally this involves a considerable limitation in the selectionof the dyestuffs and even those apt for this purpose are unsatisfactorywith respect to the fastness properties and may suffer from theafter-treatments (such as denitration in the case of nitrocelluloseetc.). The use of dyestuffs in finely dividedform again meets withdifficulties, such as blocking of the spinning orifices, deficiency oflustre and solidity of the fibre etc. These processes in practice havebecome of little value. v

The dyeing of these fibres, especially of acetylcellulose materialaccording to the method de- I scribed under (2) also meets withdifilculties. This latter material behaves differently, compared withthe other artificial fibres. New dyeing processes had to be worked outand new dyestufis, some of them being rather expensive, had to be foundout for achieving a satisfactory result.

Under certain conditions, it ispossible to dye acetate silk with vatdyestufis from the vat, running however the risk of loss of lustre andsolidity of the silk. In the case of nitrocellulose the denitration,following the spinning operation, very often may yield a fibre which isnot uniform and thus affects adversely the dyeing.

n the contrary, the present process allows the direct production ofcolored artificial fibres, films etc. with the aid of cellulose esters,such as acetyl-cellulose, nitrocellulose, and ester-salts oi leuco vatdyestuffs or other ester-salts of bodies giving by acid oxidation acolored cornpound, without meeting with the above mentioneddisadvantages or difficulties. The present process allows the dyeing ofthe cellulose material with all the shades of the scale of colors, withgood fastness properties and without prejudice to other properties, suchas lustre solidity.

The new process is illustrated, without beinglimited, by the followingexamples:

Egample Z 1 gr. the acid sulphuric acid ester-salt ofleucodimethoxydibeuzanthrone is dissolved in 20 com. or thediethyl-ether of glycol. This solution is filtered and well mixed with250 grs. of a solution prepared with 1 part or acetyh cellulose, 4 partsof acetone and l of alcohol 95%. The homogeneous mass obtained is spunas usual, f. pressed through the spinning apparatus into air. With theaid of good circulation of air, the solvent is evaporated quickly. Thethreads thus produced are rinsed in water and in order do develop thedyeing afterwards treated at ordinary temperature in a bath containing45 grs. of sodium nitrite, 36 grs. of sulphuric acid of 66" and 10 com.of a solution of ammonium vanadate (1%) per liter. The dyed threads arerinsed again and finally dried in the usual way. Acetyl-cellulosethreads homogeneously dyed, of a fast green shade are thus obtained.

Example 2 0.5 gr. of the acid sulphuric acid ester-salt of leuco-4:4'-dimethyl 6 :6-dichlorothioindigo are dissolved in 10 ccm. of acetone andcom. of the diethyl-ether of glycol. This solution is filtered and wellmixed with 250 grs. of an acetylcellulose (prepared as indicated inExample 1). The homogeneous mass is spread in form of a thin layer on aglass plate, whereby the solvent evaporates. The film thus obtained isdetached from the plate and well rinsed. The develop ment of the dyeingproceeds in a bath of the same composition as indicated in Example 1 ata temperature of 30-40" C. A pink colored, perfectly clear andtransparent film is obtained.

Example 3 1 gr. of the acid sulphuric acid ester-salt ofleucodibenzpyrenequinone is dissolved in 20 com. of the diethyl-ether ofglycol. After filtratlon, this solution is well mixed with 200 grs. of asolution of acetyl-cellulose.

In a similar manner a mixture O 8 solution of 0.5 gr. of the ester-saltof leucotetrabromindigo, 10 com. of acetone and 200 grs. of a solutionof acetyl-cellulose is prepared.

These two mixtures are applied on thin cottonfabrlc in form'of designs,ornamentations and the solvent is evaporated at the open air. Afterwardsthe dyeing is developed at 50 C. in a bath containing per liter 4 grs.of sodium nitrite 36 grs. of sulphuric acid of 66 B. and 10 ccm. of asolution of ammonium vanadate (1%). In this manner yellow and bluerelief effects on the cotton are produced.

Emample 4 0.5 gr. of the acid sulphuric acid ester-salt ofleucodimethoxydibenzanthrone is dissolved in 20 ccm. of thediethyl-ether of glycol. This solution is filtered and thoroughly mixedwith a solution of nitrocellulose in alcohol and ether. The homogeneousmass is spread in form of a; thin layer on a glass plate and exposed toa current of air, whereby the solvent is evaporated. The film isdetached from the plate and well rinsed in water. Already duringcoagulation the development of dyeing on account of the nitrogroups ofthe nitrocellulose partly takes place. The development is completed asindicated in Example 1.

The dyed film is rinsed again and for denitration finally treated at 40C. in a. bath containing 5% of sodium sulphydrate, until it becomesperfectly transparent and supple. Thereupon it is thoroughly rinsed anddried. The film produced and dyed homogeneously fast green, shows thewell known valuable qualities of the regenerated cellulose,

Instead of the diethyl-ester of glycol, glycol itself, themono-ethyl-ester of glycol or diethylene-dioxide may be used as solventsfor the ester-salts with the same effect.

What I claim is:

1. A process for producing colored celluloseester material, whichconsists in incorporating into a solution of a cellulose-ester in any ofthe usual organic solvents an ester-salt of a leucovat-dyestuii, thesame being first dissolved in an organic solvent completely misciblewith the cellulose-ester solution, thereupon mixing such solution withthe cellulose-ester solution so as to obtain a. homogeneous mass,performing coagulation and the usual after-treatments and developing thedyeing on the regenerated cellulose-ester material by acid oxidation.

2. A process for producing colored celluloseester material, whichconsists in incorporating into a solution of a cellulose-ester in any ofthe usual organic solvents an ester-salt of a leucovat-dyestuif, bydissolving same first in glycoldi-ethylether, mixing the thus obtainedsolution with the cellulose-ester solution, performing coagulation ofthe homogeneous mass thus obtained and the usual after-treatments inknown manner and developing the dyeing on the regeneratedcellulose-ester material by acid oxidation.

3. A process for producing colored celluloseester material, whichconsists in incorporating into a solution of acetyl-cellulose in acetonean ester-salt of a leuco-vat-dyestufl, by dissolving same first inglycol-di-ethylether, mixing the thus obtained solution with theacetyl-cellulose sclution, performing coagulation of the homogeneousmassthus obtained and the usual aftertreatments in known manner anddeveloping the dyeing on the regenerated cellulose-ester material byacid oxidation.

'4. A process for producing ooloretl celluloseestermaterial, whichconsists in incorporating into a, solution'of acetyl-cellulose inacetone the ester-salt of -1euco dlmethoxy dibenzanthrone by dissolvingsame first in glycol-dl-ethylether, mixing the thus obtained solutionwith the solution of acetyl-cellulose in acetone, pertorming coagulationof the homogeneous mass thus obtamed and the usual after-treatments inknown manner and developing the dyeing on the regenerated celhnose-estermaterial by gold oxidation.

HENRY DOSNE.

